From: James Goodwin <jamesg@Filanet.com>
To: linux-hotplug@vger.kernel.org
Subject: Re: 1394 SBP-2 Drives
Date: Sat, 20 Jan 2001 23:47:50 +0000 [thread overview]
Message-ID: <marc-linux-hotplug-98003479022863@msgid-missing> (raw)
Hi,
> > > As there are a lot of device on a firewire bus, it
> probably can't use the
> > > pseudo host controller hack. And shouldn't - it's a hack, which is
> > > unfortunately necessary for usb.
> >
> > I don't know where that came from, but notice I never said
> > anything about such stuff. In fact, neither does the firewire
> > code I glanced at -- Initiator/Target is the terminology.
>
> That's from usb-storage. It's the only currently working way
> to get a device that uses the scsi command set to support
> hotplugging.
The USB storage and IEEE-1394 SBP-2 drivers (as well as ide-scsi for that
matter) serve as both scsi low-level drivers and high-level protocol drivers
for their respective busses... this is done in order to leverage the scsi
command set and higher-level block drivers and filesystems.
The primary difference between the two drivers (scsi-wise) is that the USB
storage driver registers a new virtual SCSI host for each attached USB
storage device, while the IEEE-1394 SBP-2 driver registers one SCSI host per
IEEE-1394 bus, but maps each attached SBP-2 device as a virtual SCSI ID.
> I was referring to the SPB-2 subclass of ieee1394 devices which like
> usb-storage use the scsi command set. The driver for them indeed
> is not part of the standard kernel. These disks (and scanners) are
> the hardest case. If they work everything works in terms of
> hotplugging.
The main issues currently for the SBP-2 driver (and SCSI) are how to trigger
and deal with scsi device addition or removal, and how to get drives mounted
and unmounted as appropriate. The work being done on /sbin/hotplug can
certainly be leveraged, and the scsi folk are talking about hooks to allow
for event driven addition/removal of devices (in the scsi mid-level code).
One additional issue to think about is "surprise" removal of storage devices
(e.g. recovery and error handling after mounted drives with open files are
hot-unplugged). ;-)
Cheers,
--James
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next reply other threads:[~2001-01-20 23:47 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2001-01-20 23:47 James Goodwin [this message]
2001-01-21 12:14 ` 1394 SBP-2 Drives Oliver Neukum
2001-01-21 18:38 ` James H. Cloos Jr.
2001-01-22 2:34 ` David Hinds
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